Bugs in sort and resize Column with JSONDataModel

first, I use JSONDataModel to display Json data in a grid, I found no matter I use ?defaultSortable? or "sortType" that columns can't sort.

second, I rewrite the PagedGridView.js to display Hibernate's seperated page, when I resize one page's grid column, It's ok, but when I click to next page, and resize again, the column can't resize good, Is it a bug?

Can grid be render() two times? or something wrong with my code?
I use code under:
grid.render();
grid.render();
In some time I need to render() the grid two times to refresh the grid, and then the bugs appear, the column can't resize good.

You can't call render twice - you'll end up with duplicate dom entries and the event wiring is probably getting hosed. Loading the datamodel causes the rows to be repainted. If that's not happening you need to debug thru the load process and see why your data is not being loaded.